From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison of engine designs and an analysis of detonation control, specifically focusing on the Aspin valve.
| Identifier | ExFiles\Box 144\4\ scan0075 | |
| Date | 19th April 1940 | |
| -2- Curve No.3 is the 500 c.c. Rudge. Curve No.4 is our latest over-head inlet, side valve exhaust chassis unit in the state of development where it retains all the desirable features previously mentioned. Curve No.5 is the same size of unit in six cylinder form, with slight alterations to camshaft and timing, 9.1 compression ratio, and one carburetter to each cylinder, in effect, six single cylinder units on one crank. This engine would not run below 1000 r.p.m. but it serves to show that a normal engine can easily be persuaded to give a freak result. Detonation Control. It is this factor for which the main claim can be stated for the Aspin valve. Briefly, this type of unit is claimed to be capable of running at higher compression ratios than a poppet valve engine, for the same degree of detonation control by virtue of :- (a) Low running temperature of the valve. (b) Extreme turbulence of the gas due to centrifugal action of the rotating valve. Results would seem to substantiate this claim and further even if one discounts (b), the degree of detonation control claimed, shows some improvement over a sleeve valve engine for no very apparent reason. Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} | ||